U.S. Pat. No. 6,082,324 discloses a rotary internal combustion engine, which includes a cylinder internally divided into an intake-compression chamber 10, a combustion chamber 11 and an exhaust-power chamber 12. Please refer to FIGS. 1, 2 and 3. A first eccentric rotor 20 and a second eccentric rotor 30 are provided in the intake-compression chamber 10 and the exhaust-power chamber 12, respectively. When the rotors 20, 30 rotate, blades 21, 31 pivotally mounted thereon are caused to move in a curved motion. Every blade 21, 31 has a front tip and a curved back, which closely bear against the cylinder wall 14 of the cylinder of the rotary internal combustion engine when the rotors 20, 30 rotate, so that closed spaces are formed in the intake-compression chamber 10 and the exhaust-power chamber 12 between the cylinder wall 14 and the rotors 20 and 30, respectively. In the intake-compression chamber 10, the blades 21 push forward to compress intake gas. In the exhaust-power chamber 12, the blades 31 are pushed by high-pressure gas that is produced in the combustion chamber 11 through combustion and explosion and then sent into the exhaust-power chamber 12, so that the rotor 30 is driven to rotate. When the rotor 30 rotates, it brings a power output shaft 13 to rotate at the same time.
The intake-compression chamber 10 is internally provided with a first rotational valve 22 that rotates synchronously with the first rotor 20. The first rotational valve 22 is provided with three valve holes 23. When any of the three valve holes 23 is aligned with an intake port 111 of the combustion chamber 11, the compressed gas in the intake-compression chamber 10 is admitted into the combustion chamber 11. That is, the gas in the intake-compression chamber 10 is compressed by the blades 21 to enter into the combustion chamber 11. When the compressed gas enters into the combustion chamber 11, a fuel is jetted into the combustion chamber 11 to provide a fuel-air mixture, and the fuel-air mixture is ignited to combustion and explodes to produce the high-pressure gas.
The exhaust-power chamber 12 is internally provided with a second rotational valve 32 that rotates synchronously with the second rotor 30. The second rotational value 32 is provided with three valve holes 33. When any of the three valve holes 33 is aligned with an exhaust port 112 of the combustion chamber 11, the high-temperature high-pressure gas produced through the explosion in the combustion chamber 11 is admitted into the exhaust-power chamber 12. When the high-temperature high-pressure gas rushes into the exhaust-power chamber 12, the blades 31 of the second rotor 30 is pushed to move and thereby brings the second rotor 30 and the power output shaft 13 to rotate synchronously. The exhaust-power chamber 12 is provided with an exhaust outlet 121. The exhaust from the engine is guided via the exhaust outlet 121 to an exhaust tube (not shown).
In the course of rotating in the cylinder, the first and second rotors 20, 30 must keep close contact with the cylinder wall 14 to form closed spaces between the cylinder wall 14 and the rotors 20 and 30, so as to compete the stroke of fuel-air mixture compression and the stroke of power output, respectively. However, there must be a predetermined tolerance between the cylinder wall 14 and each of the first and second rotors 20, 30 to allow the rotors 20, 30 to rotate smoothly in the cylinder. Both of the cylinder and the rotors 20, 30 are at an ambient temperature when they are not in operation. When they start operating, the combustion and explosion of the fuel-air mixture produces high temperature. The cylinder will reach a high operating temperature even if there is a cooling fluid circulating outside the cylinder wall 14 for temperature control. When the temperature thereof is raised, the cylinder and the rotors 20, 30 are subjected to thermal expansion to inevitably reduce the space left between the cylinder wall 14 and the first and the second rotor 20, 30. Therefore, it is highly important to work out a way for the rotors 20, 30 to always rotate smoothly in the cylinder at both normal temperature and high temperature.
When the first rotor 20 and the second rotor 30 rotate, the curved backs and the front tips of the blades 21, 31 closely bear against the cylinder 14 in a relative motion in order to form closed spaces in the intake-compression chamber 10 and the exhaust-power chamber 12, respectively. The front tips of the blades 21, 31 are in frictional contact with the cylinder wall 14 to thereby produce high temperature, and one of the cylinder wall 14 and the blades 21, 31 that has a lower hardness will wear gradually. In the case the cylinder wall 14 is the one that wears, the cylinder wall 14 will lose its roundness. Or, in the case the blades 21, 31 are the one that wears, the blades 21, 31 will fail to closely bear against the cylinder wall 14 to achieve the effect of forming closed spaces in the cylinder.